Apparatus for cracking hydrocarbons



J. W. COAST, JR.

APPARATUS FOR CRACKING HYDROCARBONS.

APPLICATION FILED MAR. 22, 1917. RENEWED JUNE 14, 1920.

1,348,264:. e ted Aug 3, 1920.

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'UNITED STATES PATENT OFFICE.

JOHN W. COAST, JR, OF TULSA, OKLAHOMA, ASSIG-NOR TO THE PROCESS COMPANY,A CORPORATION OF MARYLAND.

APPARATUS FOR CRACKING HYDROCARBONS.

Specification of Letters Patent.

Patented Aug. 3, 1920.

Application filed March 22, 1917. Serial No. 156,645. Renewed June 14,1920. Serial No. 389,006.

To all whom it may concern Be it known that I, JOHN W. Co s'r, Jr., acitizen of the United States of America, a resident of Tulsa in thecounty of Tulsa,

State of Oklahoma, have inventedcertainnew and useful Im )rovements inApparatus for Cracking I ydrocarbons, of which the following is a full,clear, and exact description, reference being had to the accompanyingdrawing, forming a part of this specification. I

My invention relates to improvements in apparatus for crackinghydrocarbons, and more particularly to a means for protecting stillsfrom the injurious eflects of coke or tarry coke-forming substances.

The ordinary cracking still for treating high boiling point petroleumproducts is provided with means for condensing and returning heavyfractions for further treatment in the still. This reflux condensatecomprises relatively light fractions, which, by repeated distillation,may be converted into the desired low boiling point product. However, italso includes a large percentage of heavy coke-forming fractions whichusually dropto the bottom of the still and accumulate thereon at pointswhere the still is subjected directly to the action of the intense heat.This coke or carbon is produced partly by heavy fractions in the refiuxcondensate and partly by other fractions which do not vaporize in thestill. it prevents the free transmissionof heat from the still bottom tothe liquid contents of the still, and when a suflicient quantity hasaccumulated, the still bottom becomes red hot. Some immediate steps mustthen be taken toavoid a rupture at the overheated portion of the still.In actual practice, the coke accumulates on the hot still bottom whilethe oil in the still ismaintained at a high temperature and under a highpressure, thus rendering the craclzing operation quite dangerous.

The main object of my invention is to prevent a large body of the coke,or tarry. coke--forniing substances, from accumulating in a single pileat a point where the heat is transmitted to the still. In the pro ferredform of the invention, this is ac complished by condensing the highboiling point fractions and conducting such condensate to point where itwill not be subjected directly to the intense heat at the liquidcontentsof the still.

Fig. II is a transverse section of the'still taken approximately on theline II-II, Fig. I.

The still 1, arranged above a heating chamber 2, is connected by meansof an aircooled vapor pipe 3 to a reflux condenser 4. 5 designates avapor pipe leading from the reflux condenser to a main condensing coil 6from which low boiling point product is recovered. The condensing coil.G'is preferably arranged in a water tank 7. 8 designates a return pipefor conducting reflux condensate from the condenser 4 to the still. Theair-cooled vapor pipe 3 constitutes a reflux condenser, and it isinclined to allow the condensate to iiow backwardly to the still.

The apparatus I have Sl'iOWEl is particularly adapted for use-incracking high boiling point products of distillation, such for example,as the distillates or residues resulting from the distillation of crudepetroleum. The substances to be treated are introduced into the still inany suitable manner, and any desired pressure may be obtained byregulating a valve 9, preferably located in the vapor pipe 5. Thepressure in the still is preferably greater than 50 pounds per squareinch, and the temperature of the contents of the still preferably rangesfrom about 600 F. to 800 F. Heat generated in "the heating chamber 2 istransmitted di-- rectly' through the still bottom to the liquid contentsof the still. The low boiling point vapors passing from the liquid flowthrough the vapor pipe 3 and reflux condenser 4; to. the pipe 5, leadingto the main condenser 6. The relatively high boiling point fractions arecondense in the vapor pipe 3 or in the condenser 4, such fractions beingreturned either through the inclined vapor pipe 3 or return pipe '8.This reflux condensate includes a large percentage of heavy cokeformingfractions commingled with lighter fractions, which may be redistilled toform part of the low boiling point product.

In the preferred form of the invention the end portions of the stillbottom are seated upon the walls 10 of the heating chamber, and thesewalls protect said end portions from the intense heat of the heatingchain-- her. The heat is transmitted directly through the middleportlonof the stillbottom, and :the protected end portions of the stillare maintained in 'a relatively cool condition. Divergin' con'ductors'12lead from a'furmel '13 to 06 e oekets 14 .at the endsv vthe stillbottom, where it will not interfere with the transmission of heat to theliquid contents of the still. fractionsof the reflux condensatecirculate freely from the coke pockets H and comm-ihgle with the liquidin the still. The coke in the pockets 14 is notmaterially agitated bythe circulation of the liquid in the still,

The coke is thus-trapped. and

The relatively light.

and owingto its Weight it does not tend to float or rise in the lighterliquid.

The coke pockets are preferably formed below the surface of the liquidin the still so as to permit the relatively light fractions to circulate*from the coke, and the conductors 12 are preferably submerged in thehot liquid so that the returning condensate wiil be heated before itreaches the coke pockets.

.tom and one end portion of said bottom being protected from the directaction of the heat of the heating-chamber, means 'for conducting refluxcondensate into the still, and a conductor 'for directing 'such refluxcondensate to the protected end portion of the still bottom.

2. In an apparatus for cracking petroleum hydrocarbons,-a pressure stillprovided with a heating chamber and a condenser, said heating chamberbeing below the still bot tom and one end portion of-said bottom beingprotected fromthe direct action of the heat of the heating chamber, adam arranged within the stilland associated Wlth said protected portionof said bottom to form a coke trap, a reflux condenser, and means forconducting reflux condensate from said reflux condenser to said coketrap.

In testimony that I claim the foregoing I hereunto ailix my signature.

. JOHN W. coas'r, as.

